JP2002509289A - Enhanced imaging using silhouettes to improve contrast - Google Patents

Abstract

(57) Summary The intensified display (20) includes an image display (22) and a silhouette display source (26). The image display produces a virtual image (26) that is received by the observer. The silhouette display source occurs in the path of the background light (16). The silhouette display source generates a mask corresponding to the image content of the image display. A mask is a darkened area that reduces or blocks background light. Light from the virtual image is overlaid on the background, so there is less background light where the image appears.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION

 The present invention relates to enhanced imaging techniques and displays.

An intensified display is a see-through display that overlays an image on a background. The overlaid image is a virtual image. The background is the real world view of the surrounding environment. The whole image is formed by adding light to the background. The added light corresponds to the virtual image. In the portion of the display where the image is formed, the virtual image appears transparent because light from both the virtual image and the background strikes the same photoreceptor in the observer's eyes. Since light from both light sources strikes the same photoreceptor, it will be difficult for the observer to distinguish between the image and the background. The present invention is directed to a method and apparatus for enhancing the contrast of an intensified display.

[0003]

SUMMARY OF THE INVENTION

According to the present invention, the intensified display includes an image display source and a silhouette display source. An image display source produces a virtual image of light that is to be perceived by an observer. A silhouette display source occurs in the path of the background light.

According to one aspect of the invention, a silhouette display source generates a mask corresponding to the image content of an image display. A mask is a darkened area that reduces or blocks background light. Since the light from the virtual image is overlaid on the background, there is less background light where the image appears. In some embodiments, the shape and dimensions of the mask are the same as the virtual image content created by the image display. In effect, the mask is a dark version of the virtual image content. In another embodiment, the mask surrounds an area larger than just the virtual image area.

[0005] An advantage of using a silhouette mask is that the content of the virtual image is not transparent but looks dark. Virtual images overlay and obscure objects in the background.

According to another aspect of the invention, in a telescope embodiment, the silhouette display source is located in the telescope's intermediate image plane. An advantage of positioning the silhouette display source in the intermediate image plane is that the darkened silhouette is in focus. The edge between the background and the silhouette mask,
It is clear. Another advantage is that the virtual image looks more realistic when the mask is in focus.

[0007] These and other aspects and advantages of the present invention will be better understood with reference to the following detailed description, taken in conjunction with the accompanying drawings.

[0008]

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS Overview FIG. 1 shows a block diagram of a conventional intensified display device 10. The display device 10 includes a generated image source 12 and a beam splitter 14. The image source 12 includes a lens 13 and an image plane generator 15. Light is transmitted from an image source 12 and an external ambient environment 16 to a beam splitter 14.
Is received at The light from each passes through the beam splitter and reaches the eyes E of the observer. In effect, the image produced by image source 12 is overlaid on the background field of the surrounding environment.

FIG. 2 shows an optical schematic of an intensified display 20 according to an embodiment of the present invention. The display 20 includes a virtual image display 22 and a silhouette display 26
, A controller 50, a beam splitter 24, and a mirror 28. Display 20 receives image signals 51 from image signal source 19, such as RGB signals, NTSC signals, VGA signals or other formatted color or monochrome video or image data signals. Virtual image signal 17 and silhouette image signal 5
2 is obtained from the image signal 51 by the controller 50. The virtual image signal 17 is input to a virtual image display 22 and generates light to form a virtual image in response thereto. The silhouette image signal 52 is input to the silhouette display 26 and generates a silhouette image in response. The virtual image display 22 is a flat panel display, a CRT monitor, or a virtual retinal display. The light defining the virtual image is emitted from the virtual image display 22 and passes through the beam splitter 24 to the eyes E of the observer.
Hit. The silhouette display 26 is a liquid crystal display or another transparent display device that passes background light from the surrounding environment. After passing through the silhouette display 26 and the beam splitter 24, the background light 16 hits the eyes E of the observer. The concave mirror 28 receives a part of the virtual image light from the beam splitter. Mirror 28 reflects such light back to the beam splitter and back onto observer's eye E, increasing the amount of light reaching eye E. The mirror acts like a lens and positions the virtual image at the same apparent distance as the real image.

FIG. 3 shows an alternative embodiment intensified display 20 ′. Components that perform similar functions as in the display 20 are indicated by the same part numbers. Display 20 'includes a virtual image source 22, such as a flat panel display, CRT monitor, or virtual retinal display. In addition, the display 20 'includes a beam splitter 24, a silhouette display 26, an objective lens 32, an eyepiece 34, and a controller 50. The background light passes through the objective lens 32 and is focused on an intermediate image plane coincident with the silhouette display 26. Normally, the silhouette display 26 is transparent and transmits a focused background light. The background light passes through the silhouette display 26, the beam splitter 24, and the eyepiece 34 before hitting the observer's eyes E. Light defining the virtual image is emitted from the virtual image source 22, passes through the beam splitter 24 and the eyepiece 34, and then strikes the observer's eye E. Operation FIG. 4 is an image I perceived by an observer on the conventional display 10 of FIG.
Image 36 is overlaid on background image 38. Note that the overlaid image 36 is transparent. FIG. 5 shows an image I 'perceived by a viewer on the display 20 or 20' of FIGS. 2 and 3 according to the invention. The same image I 'is shown on each of the displays 20, 20', but in practice the image from the display 20 has a blurred, defocused dark area around the overlaid image I '. Image I 'from display 20' has a sharp focused boundary for the overlaid image I '.

The virtual image 40 is generated by the virtual image display 22. At the same time, a background image 42 formed by background light from the surrounding environment is passed through the silhouette display 26. In effect, virtual image 40 is overlaid on background image 42. According to one aspect of the invention, silhouette display 26 is darkened within selected area 44 (see FIG. 6) to reduce or prevent background light from passing through such selected area 44. Such a selected area 44 corresponds to the virtual image 40 and serves as a mask 46. In one embodiment, the mask 46 matches the virtual image 40 (
(See FIG. 5). In another embodiment, mask 46 surrounds more than just virtual image 40 (see FIGS. 7 and 8).

To define a virtual image 40, the virtual image display 22 receives an image data signal 51 from a computer or other signal source 19. In one embodiment, controller 50 for silhouette display 26 also includes such an image data signal 51.
Receive. In response, controller 50 generates a masking signal 52, which darkens selected area 44 of silhouette display 26 and defines a corresponding mask 46. In one embodiment, a pixel-to-pixel pixel mask 46 (see FIG. 6) is generated, in which case the silhouette display 2
In 6 there is a corresponding pixel darkened. In another embodiment, in addition to one-to-one pixel masking, additional pixels on silhouette display 26 are darkened to provide a virtual image 4.
Other portions within or around the range of 0 are masked (see FIG. 8).

The images shown in FIGS. 5 and 7 include only one virtual image 40 and one mask 46, but in alternative embodiments, multiple images 40 and mask 4 that are observable at a given time.
There are six. Similarly, although only one mask is shown in each of FIGS. 6 and 8, in alternative embodiments, a plurality of darkened regions 44 and masks 46 are formed.

In one embodiment, silhouette display 26 includes virtual image source display 2.
2 has the same pixel resolution. In another embodiment, silhouette display 26 has a different resolution (eg, lower or higher resolution) than virtual image display 22. Due to the varying resolution, the mapping of the virtual image 40 to the mask 46 is different from the one pixel to one pixel case. For every pixel of the virtual image display 22, at least one pixel of the silhouette display 26 is darkened. However, the darkened pixels of the silhouette display 26 may surround one or more pixels of the image display 22 (eg, if the silhouette display 26 has a lower resolution than the virtual image display 22). According to one embodiment, the silhouette display 26 is a transparent liquid crystal display (“LCD”).
") Formed by the panel. The LCD panel can specify the pixel accuracy. When a pixel is activated, the area of the pixel on the panel darkens to reduce or prevent the passage of background light.

Although the controller 50 is shown as receiving the image data signal 51, in an alternative embodiment, the processor that generates the image data signal 51 for the display 22 acts as a controller that generates the masking signal 52. Also fulfills. Virtual Retina Display FIG. 9 is a block diagram of a virtual retina display 22 that generates and scans light to produce a color or monochrome image having a narrow-panoramic field of view and low-high resolution. The display 22 includes an image data interface 111 that receives the virtual image signal 17 (see FIG. 2 or 3) from the controller 50. The image data interface 111 generates a signal for controlling the light source 112. The light modulated with the video information corresponds to an image element (eg, an image pixel) scanned over the retina of the observer's eye E, whereby an erect virtual image is perceived.

The virtual image signal 17 is a video or other image signal, such as an RGB signal, an NTSC signal, a VGA signal or other formatted color or monochrome video or graphics signal. An exemplary embodiment of the image data interface 111 extracts a color component signal and a synchronization "SYNCH" signal from the received image signal. In embodiments where the image signal embeds red, green and blue components, the red signal is extracted and sent to a modulator to modulate the red point source output. Similarly, the green signal is extracted and sent to a modulator to modulate the green point source output. The blue signal is extracted and sent to the modulator to modulate the output of the blue point light source.

Light source 112 includes one or more point light sources. To generate a monochrome image,
Typically, a single monochromatic emitter is used. For color imaging, multiple light emitters (e.g., red point, green point and blue point light sources) are used. Preferably, the emitted light is spatially coherent. Exemplary light emitters include color lasers, laser diodes or light emitting diodes (LEDs). Typically, LEDs do not output coherent light, but in some embodiments, lenses are used to reduce the apparent size of the LED light source to achieve a more uniform wavefront. In one preferred LED embodiment, a single mode monofilament optical fiber receives the LED output and defines a point source, which outputs light that approximates coherent light.

When the light emitter is externally modulated, display device 22 also includes a modulator responsive to image data signals received from image data interface 111. The modulator modulates the visible light emitted by the light emitter to define the image content for a virtual image to be scanned onto the observer's eyes. The modulator is an acousto-optic, electro-optic or micro-electro-mechanical modulator. Further details regarding these and other embodiments of the light source 112 can be found in "Virtual Retina Display With Fiber Optic Point Sources"
US Patent Application Serial No. 08 / 437,818, filed May 9, 1995, entitled "Virtual Retinal Display with Fiber Optic Point Source"),
Hereby incorporated by reference. According to an alternative embodiment, the light generated by the light emitter or point source is modulated to include a red component, a green component, and / or a blue component at a given point (eg, a pixel) of the resulting image. Is done. Each beam of the point source is modulated to introduce a color component at a given pixel.

The optical subsystem 114 receives light output from the light source 112 either directly or after passing through the scanning subsystem 116. In some embodiments, the optical subsystem collimates the light. In another embodiment, the optical subsystem focuses the light.
Undisturbed, the light converges to the focal point and then diverges beyond such a point. However, when the converging light is deflected, the focus is deflected. The pattern of deflection defines the pattern of focus. Such a pattern is called an intermediate image plane.

The emitted light 136 is deflected by the scanner subsystem 116 along a predetermined pattern, such as a raster pattern. In alternative embodiments, the image element can be scanned over the eye using another display format, such as vector imaging. In one embodiment, scanning subsystem 116 receives horizontal and vertical deflection signals from image data interface 111. The scanning subsystem 116 is located after the light source 112 and before or after the optical subsystem 114. In one embodiment, scanning subsystem 116 includes a resonant scanner for performing horizontal beam deflection and a galvanometer for performing vertical beam deflection. The horizontal scanner receives a drive signal having a frequency defined by the horizontal synchronization signal extracted by the image data interface 111. Similarly, the galvanometer acting as a vertical scanner receives a drive signal having a frequency defined by the vertical synchronization signal VSYNC extracted at the image data interface 111. Preferably, the horizontal scanner has a resonance frequency corresponding to the horizontal scanning frequency. In alternative embodiments, the scanning subsystem 116 instead includes an acousto-optic deflector, an electro-optic deflector, a rotating polygon, or a galvanometer to provide horizontal or vertical light deflection. In some embodiments, two identical types of scanning devices are used. In other embodiments, different types of scanning devices are used as horizontal and vertical scanners.

The light emitted from the display 22 is deflected by the beam splitter 24 (see FIGS. 2 and 3) and directed to the eyes E of the observer. In the embodiment of FIG. 3, an eyepiece 34 is also included. An advantage of using a superior and advantageous effect silhouette mask is that the contents of the virtual image appear dark rather than transparent. The virtual image overlays and covers the background object. The advantage of positioning the silhouette display source in the image plane is that the darkened silhouette is in focus. There is a sharp edge between the background and the silhouette mask. Another advantage is that the virtual image looks more realistic when the mask is in focus.

While a preferred embodiment of the invention has been illustrated and described, various alternatives, modifications and equivalents may be used. Therefore, the above description does not limit the scope of the invention, which is defined by the appended claims.

[Brief description of the drawings]

FIG. 1 is a block diagram of a conventional intensified display.

FIG. 2 is an optical schematic diagram of an intensified display according to an embodiment of the present invention.

FIG. 3 is an optical schematic diagram of an intensified display according to another embodiment of the present invention.

FIG. 4 is a diagram of an image generated by the display of FIG. 1;

FIG. 5 is an illustration of an image generated by the display of FIG. 2 or 3 according to an embodiment of the present invention.

FIG. 6 is an illustration of the silhouette display 26 of FIG. 2 or 3 with a masked area according to an embodiment of the present invention.

FIG. 7 is an illustration of an image generated by the display of FIG. 2 or 3 according to an embodiment of the present invention.

FIG. 8 is an illustration of the silhouette display 26 of FIG. 2 or 3 with an alternative masked area according to an embodiment of the present invention.

FIG. 9 is an optical schematic diagram of an embodiment of the virtual retina display of the virtual image source of FIGS. 2 and 3;

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Claims (19)

[Claims] 1. A display device (20/20 ′) for an observer to perceive a virtual image overlaid on a background light (16), the virtual image display (22) producing a virtual image (36, 40); A silhouette display (26) in the path of the background light, the silhouette display having a transparent display area, and further controlling the amount of background light passing through a portion of the transparent display area of the silhouette display. An observer receives light defining a virtual image from the virtual image display, receives background light via the silhouette display, wherein the background light is reduced within a portion of the silhouette display, and wherein the reduced background of the silhouette display is included. The display device, wherein the light portion forms a mask (46) for the virtual image (40). 2. A virtual image display, wherein the virtual image display is oriented to emit a light beam along a first set of optical paths towards an observer's eye, the virtual image display being aligned with background light in response to an image signal. The display device according to claim 1, wherein the display device is a scanning retinal display that generates one image. 3. The virtual image display is a flat panel display.
The display device according to claim 1. 4. The system of claim 1, further comprising an objective lens for background light, wherein the silhouette display is positioned in an intermediate image plane of the background light so that the mask is in focus. Or the display device according to 3. 5. The display device according to claim 1, wherein the background light does not pass through the reduced background light part of the silhouette display and forms a darkened mask. 6. The silhouette display includes a plurality of selectively drivable pixels, and the controller selectively controls an amount of background light passing through any given pixel of the silhouette display. The display device according to claim 2, 3, 4, or 5. 7. A virtual image display comprising a first number of pixels different from the number of pixels in the plurality of selectively drivable pixels of the silhouette display.
7. The display device according to claim 6, having a resolution sufficient to display (40). 8. A virtual image display, comprising: a light source (112) for generating a temporally modulated beam of light in response to an image signal (27); a virtual light source (112) oriented to receive the modulated beam of light; A scanning assembly operable to scan the modulated beam of light received through the provided scanning pattern.
8. The display device according to 2, 4, 5, 6, or 7. 9. The display device of claim 8, wherein the scanning assembly comprises a resonant scanner. 10. The light source of claim 1, wherein the background light source is an external environment.
10. The display device according to 5, 6, 7, 8 or 9. 11. An image source (22) having an image output and operable to emit light forming a virtual image (40, 36); a beam having a first input, a second input, and a combiner output. Combiner (
24) wherein the beam combiner is positioned to receive light emitted by the image source at a first input and to receive light from a background at a second output;
The beam combiner is operative to generate a combined image including the light received at the first input and the second input, and to output the combined image at the combiner output, and further comprising the second input and the background. A first region operable to send light from the background to the second input with a first decay;
A second region (46) operable to send light from the background to the second input with a second attenuation different from the first attenuation (20/20 '). 12. The display according to claim 11, wherein the silhouette is an electronically controlled silhouette. 13. An image signal source (19) coupled to an image source and operative to provide an image signal (51) representing a virtual image; and an input coupled to the image signal source (19) and an output to a silhouette (26). 13. The display of claim 12, further comprising an electronic controller (50) coupled. 14. The display of claim 13, wherein the silhouette comprises a liquid crystal panel. 15. The electronic controller includes an image tracking circuit operable to extract a position of a selected portion of the image from the image signal (51) and generate a silhouette signal indicating the position of the selected portion. 2. The method of claim 1, further comprising: locating a second area that overlays a portion of the selected portion in response to the silhouette signal.
15. The display according to 3 or 14. 16. The display according to claim 15, wherein the second area is shaped to correspond to the selected image portion. 17. The second area (46) is larger than the selected image portion.
The display according to claim 15. 18. The method of claim 11, wherein the second attenuation is greater than the first attenuation.
18. The display according to claim 13, 13, 14, 15, 16 or 17. 19. The display according to claim 11, wherein the beam combiner (24) comprises a beam splitter.